Thursday, July 29, 2010

Multiple episodes of Antarctica Record Warming 3-4°C Higher than Present

Thesettled science a.k.a. climatology is struggling to explain why ice core samples show that both Greenland and Antarctica have had multiple interglacial periods over the past several hundred thousand years during which temperatures exceeded today's "record high" temperatures by a very considerable 3-4°C, despite the global climate "control knob" a.k.a. CO2 remaining at least 30% lower than the present. The latest attempt is a paper just published, Interhemispheric coupling, the West Antarctic Ice Sheet and warm Antarctic interglacials:

Abstract. Ice core evidence indicates that even though atmospheric CO2 concentrations did not exceed ~300 ppm at any point during the last 800 000 years, East Antarctica was at least ~3–4 ◦C warmer than preindustrial (CO2 ~280 ppm) in each of the last four interglacials. During the previous three interglacials, this anomalous warming was short lived (~3000 years) and apparently occurred before the completion of Northern Hemisphere deglaciation. Hereafter, we refer to these periods as “Warmer than Present Transients” (WPTs). We present a series of experiments to investigate the impact of deglacial meltwater on the Atlantic Meridional Overturning Circulation (AMOC) and Antarctic temperature...

The paper attempts to explain this phenomenon on meltwater from Antarctic glaciers causing alterations in ocean oscillations resulting in a seesaw coupling between the Arctic and Antarctic glaciation and deglaciation, perhaps similar to what we are witnessing today as shown in the Arctic and Antarctic sea ice anomaly charts in the right column→→. I find no mention in the paper why CO2 was not a "control knob" in the past but is now, why "record higher" temperatures occurred multiple times over the past 350K years, and why the "positive feedback from decreased albedo" didn't cause the planet to spin out of control each of those times. Of course it could just be interacting Milankovitch, solar, and oceanic cycles explaining all of this and today's climate, but that would be too simple. see Occam's razor.

Temperature graph at top, temperature anomalies at right of y axis, thousands of years before present along x axis